Drug sniffing dogs have been utilized for many years in areas such as ports and airports to sniff for and locate illegal drugs. A handler leads the dog to each container or luggage, and the dog attempts to pick up a scent of any drugs. The handler is the one who directs the search and the dog is merely used as a sniffing mechanism. The dog searches the target (a person, a vehicle, luggage, a warehouse, etc.) for any odor it has been trained to recognize and gives the handler a final response if any such odor is detected.
Similarly, bomb sniffing dogs have been utilized at airports and other locations to sniff for and locate bomb devices. Again, a handler guides the dog to search luggage and other items and locations. These techniques are very simplistic and have many flaws.
Although many explosives and thousands of pounds of drugs have been uncovered in this manner, “handler driven” canine detection has some disadvantages. One disadvantage is the narrowness of the search. For example, if the handler does not stop every single person walking through an airport to let the dog search them for explosives, then the dog may miss a person carrying a bomb under his shirt. The dog can only search those targets that the handler instructs the dog to search. In other words, the dog only gets to search those targets that the handler deems are necessary to search. Another disadvantage is the obtrusiveness of the search. It is very obvious that officers are searching for something if a handler is leading a dog around while pointing to things for the dog to sniff.